After the rapid development of inorganic integrated circuits, a first organic circuit in a real sense did not appear until 1995 when the Philips Laboratory achieved a series of basic circuit units such as inverter using pentacene and polyvinyl thiophene, etc. (Science 1995, 270, 972), thus stirring up a new chapter of studying organic field effect circuit. Organic materials have many inherent advantages, such as simple film formation and fabrication process, wide source of materials, good compatibility with flexible substrates, and easy modulation of electrical properties, compared with inorganic materials (Nature, 2001, 414, 599; Chemical Reviews 2012, 112, 2208; Nature 2013, 499, 458; Journal of the American Chemical Society 2004, 126, 8138). Thus, the research of organic field effect transistors and circuits had got a rapid development and progress in the past decade. In recent years, the research of organic field effect circuits mainly focuses on preparation of organic thin film field effect circuits (Applied Physics Letters 1998, 72, 2716; Advanced Materials 2003, 15, 1147; Nature Materials 2003, 2, 678; Chemistry of Materials 2011, 23, 733). However, there are a large number of grain boundaries and high-density structural defects in organic thin films, which can significantly impact performance of devices and circuits (Advanced Materials 2006, 18, 2320). The appearance of organic single crystal becomes a solution to this problem. Since organic single crystal has no grain boundary and has a good π-π orbital overlap, the trapping density of charge can be reduced effectively. Therefore, it is possible to prepare an organic single crystal field effect circuit, to improve device performance.
Currently, few articles put emphasis on preparation of organic single crystal field effect circuits, which can be divided into two categories based on different configurations of a device (that is, the up-down position between a source/drain electrode and a semiconductor), one is top-contact organic single crystal field effect circuits (Advanced Materials 2009, 21, 3649; Advanced Materials 2009, 21, 4234; Applied Physics Letters 2009, 94, 203304; Advanced Materials 2010, 22, 3938; Advanced Materials 2012, 24, 2588), and the other is bottom-contact organic single crystal field effect circuits (Applied Physics Letters 2006, 89, 222111; Nano Letter 2007, 7, 2847). For the first category of top-contact organic single crystal field effect circuits, Hu Wenping Research Group has prepared a bootstrap inverter by vacuum depositing gold as electrodes using nanobelt which serves as a mask based on two single crystals of anthracene derivative (Advanced Materials 2009, 21, 3649). Uemura Research Group has prepared a complementary inverter by vacuum depositing gold and calcium as electrodes based on a single crystal of single rubrene (Advanced Materials 2010, 22, 3938). Bao Zhenan Research Group has obtained basic circuit units of an inverter by preparing C60 and TIP S-pentacene single crystal on a silicon dioxide substrate with a liquid phase method, and then vacuum depositing gold as electrodes (Advanced Materials 2012, 24, 2588). They are common in preparing top-contact organic single crystal field effect circuits directly on organic single crystals by means of a conventional approach of vacuum mask deposition. However, this approach has several drawbacks. On one hand, prepared electrodes have larger size, wires are less precise, shapes of patterns are limited, and complex patterns cannot be prepared. On the other hand, during deposition of an electrode, thermal radiation may cause some damage to an organic semiconductor (Advanced Materials 2008, 20, 2947; Advanced Materials 2008, 20, 1511), thus affecting performance of a device. In order to address the above drawbacks of the approach of vacuum mask deposition, Hu Wenping Research Group also proposed two approaches: “gold film stamp” and “Nanobelt electrode” for preparing an organic single crystal circuit (Applied Physics Letters 2009, 94, 20304; Advanced Materials 2009, 21, 4234), which successfully avoid damages of heat radiation to an organic semiconductor. Since such approach prepares a device by using a probe to micro-manipulate a gold film and a nanobelt electrode, it is only suitable for preparing a single device, and not suitable for preparing a more complex circuit, thus not having high integration level. In order to solve problems such as heat radiation damage and low integration level when preparing top-contact organic single crystal circuits, the researchers further develop the second category of bottom-contact organic single crystal field effect circuits. Bao Zhenan Research Group has prepared a complementary inverter on a silicon dioxide substrate based on n-type and p-type organic single crystals (Applied Physics Letters 2006, 89, 222111; Nano Letter 2007, 7, 2847). The features of this approach are: firstly, preparing electrodes on a substrate with photolithography or an approach of vacuum mask deposition, and then combining organic single crystals with the electrodes and an insulating layer via electrostatic force, to finally form a device. The advantage of this approach is that it can address the problems of heat radiation damage and low integration level. However, this approach also has some drawbacks: on one hand, in structure of an organic single crystal field effect circuit with bottom-contact reported presently (as shown in FIG. 1), the configuration that electrodes protruding from a surface of an insulating layer is more suitable for crystals with larger size such that sizes of used crystals are limited. When an organic micro/nano semiconductor is placed onto the electrodes, as shown in FIG. 2, the configuration that electrodes protruding from the surface of the insulating layer may result in incomplete fit between the organic single crystal and the insulating layer, thereby resulting in electrode steps. Further, due to poor conductivity of an organic semiconductor, it is difficult to transport carriers in the unfitted portion, which may cause field effect performance of the device to degrade, and even cause the device to lose field effect performance. On the other hand, the presently reported bottom-contact organic single crystal field effect circuits are prepared on rigid substrates, which may cause contact quality between the semiconductor and electrodes to be poor, and may cause a defect to be produced, resulting in reduced device performance. Therefore, it is desirable to provide a novel method for preparing an organic single crystal field effect circuit that can eliminate heat radiation damage to the organic semiconductor and can achieve an organic single crystal with high performance, flexibility, high integration, and applicability to various sizes.